In recent years, an environment where the information network is accessible anytime and anywhere has been developed as is called a ubiquitous information society. In such an environment, individual identification technologies have attracted attention.
In these technologies, an identification (ID) number is assigned to each object so that the history of the object can be recognized to be utilized in production, management, or the like. Above all, semiconductor devices capable of wirelessly transmitting and receiving data have started to be used.
One of the individual identification technologies having attracted attention utilizes an RFID (radio frequency identification) tag as a semiconductor device that is capable of wirelessly transmitting, receiving, storing, and erasing data. The RFID tag is also called an IC (integrated circuit) tag, an RF tag, a wireless tag, an electronic tag, an IC chip, or a wireless chip. Data is transmitted and received to and from the RFID tag using a device for reading and writing data (hereinafter, referred to as a reader/writer). The individual identification technologies using the RFID tag have started to be used for production, management, or the like of an individual object, and application to personal authentication has also been promoted.
An RED tag has an antenna for wirelessly transmitting and receiving electromagnetic waves, radio waves, or the like including data, and an integrated circuit as well as the antenna is included in the RFID tag. Some RFID tags generate, with use of a rectifier or a rectifier circuit included in the RFID tags, a DC voltage from electromagnetic waves, radio waves, or the like transmitted from an external device such as a reader/writer, and operate with a stable, constant voltage obtained through a controller such as a regulator circuit.